Bean flower thrips (Megalurothrips sjostedti) is a key pest of cowpea (Vigna unguicalata) in Africa. To better understand the interaction of M. sjostedti to cowpea cultivars to improve management efforts, we investigated the repellent properties of volatiles of four cowpea cultivars, namely Ex-Luanda, Machakos, Ken Kunde 1 and Katumani 80 at different phenological stages. Bioassays were conducted to study host preference and gas chromatography–mass spectrometry for chemical analysis of volatiles. Our results showed no significant preference of females M. sjostedti for any cowpea cultivars tested in preference assays. However, in olfactometer, the volatiles emitted during the vegetative stage of only Ex-Luanda, Machakos and Katumani 80 cultivars were repellent to females, while only Ken Kunde 1 was repellent to males. Volatiles from flowers of Ken Kunde 1 were attractive to females, whereas volatiles from the flowers of Katumani 80 were repellent, respectively. Ex-Luanda and Machakos elicited neutral response. Flowers of Machakos 66 and Ex-Luanda cultivars were repellent to males, while Katumani 80 and Ken Kunde 1 were neutral. The volatile analysis showed that (E)-β-ocimene and 1-octen-3-ol were unique to the volatile profile of Katumani 80 flowers. Previous study showed that (E)-2-hexenal and hexanal were only abundant in the vegetative stage of Katumani 80. (E)-2-hexenal was repellent to the females at a concentration of 0.01% but not at 1%. Hexanal, (E)-β-ocimene and 1-octen-3-ol elicited a neutral response from females at 0.01% and 1%. Our study indicates that (E)-2-hexenal could be useful in the development of semiochemical-based repellent tools for M. sjostedti management.

中文翻译：

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豆花蓟马（Megalurothrips sjostedti）对不同cow豆品种营养和花卉挥发物的行为反应。

豆花蓟马（Megalurothrips sjostedti）是非洲cow豆（Vigna unguicalata）的主要害虫。为了更好地了解M. sjostedti与cow豆品种的相互作用以改善管理效果，我们研究了在不同物候阶段，Ex-Luanda，Machakos，Ken Kunde 1和Katumani 80这四个cow豆品种的挥发物的驱避特性。进行了生物测定以研究宿主偏好，并使用气相色谱-质谱法对挥发物进行化学分析。我们的结果表明，雌性M. sjostedti没有明显的偏爱适用于在偏好分析中测试的任何cow豆品种。然而，在嗅觉计中，仅Ex-Luanda，Machakos和Katumani 80个品种在营养阶段释放的挥发物对雌性具有排斥作用，而Ken Kende 1仅对雄性具有排斥作用。Ken Kunde 1的花朵中的挥发物对女性具有吸引力，而Katumani 80的花朵中的挥发物则具有驱避作用。前罗安达和马查科斯引起中立反应。Machakos 66和Ex-Luanda品种的花对雄性具有排斥性，而Katumani 80和Ken Kunde 1是中性的。挥发物分析表明，（E）-β -ocimene和1-辛烯-3-醇是Katumani 80花的挥发物特征所特有的。先前的研究表明（E）-2-己烯醛和己醛仅在Katumani 80的营养期丰富。（E） -2-己烯丙醇对雌性的排斥力为0.01％，但不为1％。己醛，（E）-β -ocimene和1-辛烯-3-醇引起雌性的中性反应分别为0.01％和1％。我们的研究表明（E） -2-己烯醛可能在开发基于化学信息的驱蚊工具中对舍氏梭菌进行管理。